The goal of this project is to make available The 90+ Study database as a resource to the greater scientific community through the National Archive of Computerized Data on Aging (NACDA). The 90+ Study is one of the largest population-based studies investigating dementia and aging in the oldest-old, people aged 90 and older. The study was initiated in 2003, enrolled nearly 1,600 participants, and has collected a wealth of longitudinal data including demographics, medical history, medication and vitamin use, lifestyle habits, family history, physical and neurological exams, neuropsychological tests, physical and leisure activities, functional abilities, assistive devices, and causes of death. Data collected in the 1980-1990s on several lifestyle practices, medial history, medication and vitamin use by the Leisure World Cohort Study are also available for these participants. Neuropathological evaluations exist for a subset of participants who agreed to brain autopsy upon death. We propose to create de-identified datasets and self-explanatory detailed documentation of the data collected throughout the 13+ years of The 90+ Study. We will supply these to NACDA for archiving and distribution while protecting the confidentiality of the participants. Data from only deceased participants will be included in this effort. Archiving data through NACDA will ensure that all data will be preserved and easily available for years to come. The research team consists of the investigators who initiated The 90+ Study and the Leisure World Cohort Study and have been responsible for all aspects of the studies including concept, design, choice of assessments, data collection, statistical analysis, and publications. They are the ideal people to undertake this proposal and are strongly committed to collaborations and sharing of these rich databases The large population-based sample, extreme old age of the participants, frequent evaluations, high retention rate, and wide variety of information make these data unique. The archived data can be used to study a variety of outcomes relevant to the health of the oldest-old including, but not limited to, dementia, disability, frailty, and mortality. We anticipate the scietific resource created through this proposal will be used by researchers to explore new scientific hypotheses, provide pilot data for new grant applications, combine data with other oldest-old studies for larger sample sizes, and complement other longitudinal databases in NACDA, with the ultimate goal of advancing the scientific knowledge about this understudied group The 90+ Study has already contributed greatly to the knowledge of our oldest individuals but public availability of these data will extend its utility. Given the public health burden that our society faces with this fast-growing group, this data archiving effort represents a cost-effective strategy to promote research that can help improve the health of our oldest citizens.